#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pll;
typedef pair<int, int> pii;
typedef pair<double, double> pdd;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<double> vd;
typedef vector<string> vs;
typedef vector<vi> vvi;
typedef vector<vvi> vvvi;
typedef vector<vll> vvll;
typedef vector<vvll> vvvll;
typedef vector<pii> vpii;
typedef vector<vpii> vvpii;
typedef vector<pll> vpll;
typedef vector<vpll> vvpll;
typedef vector<pdd> vpdd;
typedef vector<vd> vvd;
#define yn(ans) printf("%s\n", (ans)?"Yes":"No");
#define YN(ans) printf("%s\n", (ans)?"YES":"NO");
    template<class T> bool chmax(T &a, T b) {
	if (a >= b) return false;
	a = b; return true;
}
template<class T> bool chmin(T &a, T b) {
	if (a <= b) return false;
	a = b; return true;
}
#define FOR(i, s, e, t) for ((i) = (s); (i) < (e); (i) += (t)) 
#define REP(i, e) for (int i = 0; i < (e); ++i) 
#define REP1(i, s, e) for (int i = (s); i < (e); ++i)
#define RREP(i, e) for (int i = (e); i >= 0; --i)
#define RREP1(i, e, s) for (int i = (e); i >= (s); --i)
#define all(v) v.begin(), v.end()
#define pb push_back
#define qb pop_back
#define pf push_front
#define qf pop_front
#define maxe max_element
#define mine min_element
ll inf = 1e18;
#define DEBUG printf("%d\n", __LINE__); fflush(stdout);
template<class T> void print(vector<T> &v, bool withSize = false) {
	if (withSize) cout << v.size() << endl;
	REP(i, v.size()) cout << v[i] << " "; 
	cout << endl;
}
mt19937_64 rng((unsigned int) chrono::steady_clock::now().time_since_epoch().count());

int __FAST_IO__ = []() {
	std::ios::sync_with_stdio(0);
	std::cin.tie(0);
	std::cout.tie(0);
	return 0;
}();

#define TESTS int t; cin >> t; while (t--)
#define TEST 
int main() {
    TESTS {
    	int N; ll X;
    	cin >> N >> X;
    	vpll p;
    	ll r = X;
    	REP(i, N) {
    	    int c;
    	    cin >> c;
    	    if (!(X >> c & 1)) {
    	        ll f = 1ll << c;
    	        ll d = X % f;
    	        if (X < (1ll << c)) {
    	            chmax(r, 1ll << c);
    	  //          printf("r %d %lld\n", c, r);
    	        } else {
    	            p.pb({X - d - 1, X - d + f});
    	  //          printf("l %d %lld %lld\n", c, X - d - 1, X - d + f);
    	        }
    	    }
    	}
    	sort(all(p));
    	ll ans = 4e18;
    	for (int i = 0; i < p.size(); ) {
    	  //  printf("%lld %lld %lld\n", p[i].first, p[i].second, r);
    	    chmin(ans, 2 * (r - p[i].first));
    	    int j = i;
    	    while (j < p.size() && p[i].first == p[j].first) {
    	        chmax(r, p[j].second);
    	        ++j;
    	    }
    	    i = j;
    	}
    	chmin(ans, 2 * (r - X));
    	printf("%lld\n", ans);
    }
    
    return 0;
}